any obd1 b-series will pretty much be the exact same difficulty. If you decide to go b16, make sure you get one that is obd1 or 2 (if you go two, you have to do a little more work, but not much) Anyways, your going to need a b-series tranny, b-series axles, Del sol VTEC shift linkage (integra ones won't work for you) and b-series mount brakets.
With the GSR swap, the only "extra" thing that you will have to do is run 2 more wires, vs the like 2 or 3 with a b16 swap. I have a GSR swap in my sol and if you have the money, i would HIGHLY suggest this. A b16 just doesn't have alot of trq. At the wheels, they dyno at LESS then 100 ftlbs. The sol is a tad heavier then a civic hatch, so keep that in mind.
Other swaps can be a b18b or an ITR (ITR = lots of money). b18b's are not the fastest stock, but parts for them are extremly cheap. If you do a search for "b18b all motor", you will see a post by me about a b18b with just cams, springs, retainors, and milled head, and this motor just "KILLED" a type R's dyno.
